Yes - all phones have a relatively small sensor, but most importantly, a really small len or lens.

These sensors have their own sensitivity and this sensitivity (I mean gain) can be adjusted a bit - the higher the gain, the higher the noise is - and other than the sensor, the amount of light coming to sensor is what matters.

As all of these phones have relatively small camera holes, the amount of light is very limited. On professional cameras, there is a large objective (lens system) which collects a large amount of light into the sensor.
Then it is much easier to play with aperture and exposure times and the gain of the sensor.
Thus, depth of field can be also adjusted to make desired images.

So a phone's camera has limited possibilities to work with. It doesn't mean it is unable to make photos in darker environment, I think Pro1 has similar abilities like other phones.

Also, there are applications where some parameters can be given to make some special photos also with a phones.